PDF Ebook Probiotic-Supplemented Soy Bar Effects on Resistance to Infection By Listeria Monocytogenes
Probiotics are living microorganisms that help regulate the gastrointestinal tract. The aim of this project was to investigate the benefits of probiotics and their inhibitory effect on Listeria monocytogenes EGD. The well diffusion assay was conducted to screen the probiotics for inhibition of L. monocytogenes EGD. A diet was created out of a soy protein bar supplemented with the probiotics to be used in our in vivo test using a mouse model.
Three groups of mice were fed for two weeks with three different diets, one diet each, Control diet with no probiotic, ADH diet with Lactobacillus acidophilus ADH, and B6 diet with Bifidobacterium animalis B6. Each group was subdivided into two different groups, one of them would be challenged with L. monocytogenes EGD and the other group would not (control group). After 14 days of feeding, the mice were challenged intragastrically with10 8 CFU/ml L. monocytogenes EGD. At day 3 post-infection, the mice were euthanized. Of the samples collected, the colon and cecum were tested for probiotic concentration. The spleen and liver were tested for the presence of L. monocytogenes. In the first replication, a half a log reduction of L. monocytogenes EGD in the liver was observed in the Bifidobacterium group as compared with the control group, but no significant reduction in the pathogen was seen in the Lactobacillus group for any of the samples collected. For the second trial, a one log reduction of L. monocytogenes EGD in the liver was achieved in the Bifidobacterium group, but at the same time, a one log reduction of the pathogen in the spleen was also observed in the Lactobacillus group. We also collected evidence showing that the probiotics colonized the colon and the cecum with concentrations of10 7 CFU.
The foodborne pathogen, Listeria monocytogenes, causes an invasive human infection called listeriosis. This infection is predominant among immunosuppressed individuals, such as pregnant women, HIV-positive and cancer patients, and the unborn fetus. Its symptoms are severe and include meningitis, and miscarriage, among others. This pathogen is an intracellular microorganism that is capable of crossing the intestinal barrier, fetoplacental barrier, and blood-brain barrier. L. monocytogenes has an overall mortality rate of30%.
Microorganisms have become resistant to antibiotic medications in such a short time that researchers are having trouble finding new antibiotics. Another disadvantage of antibiotics is that they can affect the natural microflora in the body. This is why scientists are trying to find alternative ways to fight pathogens. Using probiotics is one way to do that. Probiotics are microorganisms that affect the intestinal tract in a positive way when ingested in an appropriate amount. Some studies have shown that benefits of ingesting probiotics can include: stimulation of the host immune system, lowering cholesterol, expressing anti-cancer activities, and suppressing the growth of undesirable microorganisms, including pathogens. By suppressing undesirable microorganisms, probiotics assist in maintaining a balanced microflora in the human gastrointestinal tract. The documentation of these benefits has increased the interest and demand for probiotic supplemented food products. Some probiotics in the current market include: Lactobacillus acidophilus, Lactobacillus rhamnosus GG and Bifidobacterium longum. These and other probiotics are marketed in a variety of forms, including powders, milk, yogurts, and capsules.
CONTENTS
ACKNOWLEDGEMENTS
LIST OF FIGURES
LIST OF TABLES
ABSTRACT
Chapter
1 INTRODUCTION
2 LITERATURE REVIEW
2.1 Soybeans
2.1.1 Health benefits of soy
2.1.2 Examples of functional soy foods
2.2 Probiotics
2.2.1 Lactobacillus species
2.2.2 Bifidobacterium species
2.2.3 Other probiotics
2.3 Probiotic preservation
2.4 Listeria monocytogenes
2.4.1 Distribution
2.4.2 Incidence and treatment
2.4.3 Pathogenecity
2.4.4 Virulence factors
2.4.5 Cytokines induction
2.5 Probiotic effects on Listeria monocytogenes EGD
3. MATERIAL AND METHODS
3.1 Probiotic selection
3.2 Design of Selective media for probiotics
3.3 Experimental diet
3.3.1 Probiotics Freeze drying
3.3.2 Soy protein energy bar raw materials
3.3.3 Soy protein energy bar preparation
3.3.4 Mouse diet ingredients
3.3.5 Diet preparation
3.3.6 Storage conditions
3.3.7 Microbial analysis
3.4 Listeria monocytogenes strain selection
3.5 Animal treatments
3.5.1 Preliminary diet study
3.5.2 Dietary treatment groups
3.5.3 Listeria monocytogenes challenge
3.5.4 Mice weights
3.5.5 Sample analyses
3.5.5.1 Colon and cecum analyses
3.5.5.2 Liver and spleen analyses
3.5.5.3 Gallbladder analyses
3.5.5.4 Cytokines analyses
3.5.5.5 Identification of colon and cecum colonies 3.6 Statistical analysis
4. RESULTS AND DISCUSSION
4.1 Probiotic selection
4.2 Selective media
4.3 Microbial analysis of the diet
4.4 Listeria monocytogenes strain selection
4.5 Mice weight. 4.5.1 Body weight from preliminary study
4.5.2 Body weight from trials
4.5.2.1 First trial
4.5.2.2 Second trial
4.5.2.3 Third trial
4.6 Samples analyses
4.6.1 Colon and cecum analyses
4.6.1.1 First trial
4.6.1.2 Second trial
4.6.1.3 Third trial
4.6.2 Liver and spleen analyses
4.6.2.1 First trial
4.6.2.2 Second trial
4.6.2.3 Third trial
4.6.3 Gallbladder analyses
4.6.4 Cytokines analyses
4.6.5 Identification of colon and cecum colonies
5. CONCLUSIONS
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
REFERENCES
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